Hydrogen production and utilization

ABSTRACT

A PROCESS FOR THE PRODUCTION OF HYDROGEN, INCLUDING CONTACTING A LIGHT PARAFFINIC HYDROCARBON SUCH AS ETHANE, PROPANE, N-BUTANE, ISO-BUTANE, N-PENTANE, ISO-PENTANE, ETC., WITH A CATALYST COMPRISING AN ACTIVE METAL SELECTED FROM THE GROUP CONSISTING OF A GROUP VIII METAL, SUCH AS PLATINUM, RHODIUM, RUTHENIUM, PALLADIUM, AD NICKEL, AND A GROUP VI-B METAL, SUCH AS CHROMIUM, MOLYBDENUM AND TUNGSTEN, IN AN AMOUNT BETWEEN ABOUT 0.5 AND 15% BY WEIGHT OF THE FINISHED CATALYST AND A PROMOTER SELECTED FROM THE GROUP CONSISTING OF GROUP I, GROUP II, RARE EARTH, AND GROUP IV-A METALS OF THE PERIODIC SYSTEM AND MIXTURES THEREOF, IN AN AMOUNT BETWEEN ABOUT 1 AND 15% BY WEIGT BASED ON THE FINISHED CATALYST, BOTH DEPOSITED ON AN INERT OXIDE CARRIER, LIQUEFYING THE EFFLUENT PRODUCT, AS BY CONDENSATION OR COMPRESSION, FLASHING THE DRY GAS PORTION CONTAINING HYDROGEN THEREFROM, IF DESIRED, FURTHER PURIFYING THE HYDROGEN BY CRYOGENIC, ADSORPTION AND DIFFUSION METHODS, ETC., SEPARATING AN UNSATURATED PORTION FROM A SATURATED PORTION OF THE REMAINING PRODUCT, AS BY DISTILLATION, ADSORPTION, SOLVENT EXTRACTION, SELECTIVE POLYMERIZATION, SELECTIVE AROMATIC ALKYLATION, SELECTIVE PARAFFIN ALKYLATION, ETC., AND RECYCLING UNREACTED PARAFFINS TO THE CONTACTING STEP. THE HYDROGEN RECOVERED FROM THE FLASHING STEP IS ALSO UTILIZED FOR THE HYDROGENATION OF HEAVY UNSATURATED HYDROCARBON MATERIALS, SUCH AS COAL LIQUIDS, BY CONTACTING THE HEAVY LIQUIDS WITH THE HYDROGEN IN THE PRESENCE OF A HYDROGENATION CATALYST, PREFERABLY OF THE SAME CHARACTER AS THE HYDROGEN-PRODUCING CATALYST, AND UNDER CONDITIONS SUFFICIENT TO HYDROGENATE THE HEAVY LIQUIDS.

United States Patent HYDROGEN PRODUCTION AND UTILIZATION Ronald A. Kmecak and Stephen M. Kovach, Ashland,

Ky., assignors to Ashland Oil, Inc., Houston, Tex. No Drawing. Continuation of abandoned application Ser.

No. 769,727, Oct. 22, 1968. This application Nov. 23,

1970, Ser. No. 92,243

Int. Cl. C01b 1/18 U.S. Cl. 208-100 5 Claims ABSTRACT OF THE DISCLOSURE A process for the production of hydrogen, including contacting a light paraflinic hydrocarbon such as ethane, propane, n-butane, iso-butane, n-pentane, iso-pentane, etc., with a catalyst comprising an active metal selected from the group consisting of a Group VIII metal, such as platinum, rhodium, ruthenium, palladium, and nickel, and a Group VI-B metal, such as chromium, molybdenum and tungsten, in an amount between about 0.5 and 15% by weight of the finished catalyst and a promoter selected from the group consisting of Group I, Group II, Rare Earth, and Group IV-A metals of the Periodic System and mixtures thereof, in an amount between about 1 and 15% by weight based on the finished catalyst, both deposited on an inert oxide carrier; liquefying the effluent product, as by condensation or compression; flashing the dry gas portion containing hydrogen therefrom; if desired, further purifying the hydrogen by cryogenic, adsorption and difiusion methods, etc.; separating an unsaturated portion from a saturated portion of the remaining product, as by distillation, adsorption, solvent extraction, selective polymerization, selective aromatic alkylation, selective paraffin alkylation, etc., and recycling unreacted paraffins to the contacting step. The hydrogen recovered from the flashing step is also utilized for the hydrogenation of heavy unsaturated hydrocarbon materials, such as coal liquids, by contacting the heavy liquids with the hydrogen in the presence of a hydrogenation catalyst, preferably of the same character as the hydrogen-producing catalyst, and under conditions suflicient to hydrogenate the heavy liquids.

This application is a continuation of Ser. No. 769,727 filed Oct. 22, 1968, and now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to a method for producing hydrogen from light hydrocarbon parafiins, separating the hydrogen from the eflluent product, and, if desired, hydrogenating heavy unsaturated hydrocarbons with said hydrogen.

At the present time, the hydrogen requirements of petroleum refineries, which are necessary for hydrogen treating operations, such as hydrogenation, hydrotreating, hydrocracking, etc., and for the production of petrochemicals, are extremely high. Hydrogen requirements are even higher in processes for treating liquids of a hydrocarbon nature which are highly unsaturated, such as liquids derived from coal. For example, coal liquids may be obtained from coal by carbonization or pyrolysis of the solid coal to produce coal tar products or by the solvent extraction of solid coal, with solvents such as tetralin, Decalin and the like to produce a solvent extract, or combinations of these techniques. The hydrocarbon liquids produced from coal are extremely complex, generally cyclic or aromatic compounds, having a high degree of unsaturation or hydrogen deficiency. Consequently, in order to process such liquids further, it is necessary to stabilize such liquids by at least partial saturation so that 3,725,246 Patented Apr. 3, 1973 they may be handled in high temperature equipment, both in distillation and catalytic processing, without extreme coking, plugging, etc. It is also necessary that such coal liquids be at least partially saturated in order to produce so-called synthetic petroleum which can then be processed in conventional manners in a petroleum refinery for the production of the usual petroleum-type products and, in some cases, some unusual products.

At the present time, the production of hydrogen for the petroleum-petrochemical industry is generally through the catalytic reforming of naphthas or the steam reforming of light hydrocarbons. The hydrogen available from catalytic reforming is rather limited and in short supply, so that more and more producers are resorting to steam reforming of light hydrocarbons to satisfy the massive hydrogen requirements of todays operations. However, even this technique has fallen short of todays demand of the petroleum refinery and it is nowhere near adequate for the production of hydrogen for the saturation of coal liquids. Another method for producing hydrogen is as a lay-product of the production of unsaturated hydrocarbons. One such process involves the pyrolysis of hydrocarbons to produce products such as acetylene, ethylene and propylene. This system has the disadvantages of high temperature and low purity of the hydrogen stream. Another possible source of hydrogen is as a by-product of processes for the dehydrogenation. of saturated hydrocarbons to produce the corresponding unsaturated hydrocarbons. While this is a relatively simple operation and large quantities of the saturated hydrocarbons are available as a raw material and at reasonable prices, these processes which have been developed have numerous drawbacks. For the most part, the processes developed to date are cyclic, adiabatic, fixed-bed, regenerative processes operating on short cycle times due to coke deposition. on the catalyst. Typically, the cycle times in these cases are about 7 to 15 minutes. Therefore, for a continuous operation, a minimum of three reactors is required with one reactor on-stream, one being regenerated, and one on standby. Multiples of this system can be utilized to increase production.

It is therefore an object of the present invention to provide a process which overcomes the above-mentioned difliculties. Another object of the present invention is to provide a process for the production of substantial quantities of hydrogen. Another and further object of the present invention is to provide an improved process for the production of substantial quantities of hydrogen from light paraflinic hydrocarbons. Still another object of the present invention is to provide an improved process for the production of hydrogen by contacting light paraflinic hydrocarbons with a highly effective catalyst. Yet another object of the present invention is to provide an improved process for the production of hydrogen by the dehydrogenation of light paraflinic hydrocarbons, separation of hydrogen from the effluent product and hydrogenation of coal liquids with the recovered hydrogen. Another and further object of the present invention is to provide an improved process for the production of hydrogen by contacting light paraflinic hydrocarbons with a novel catalyst capable of extremely long cycle periods. A further object of the present invention is to provide an improved process for the production of hydrogen, including dehydrogenating light paraflinic hydrocarbons, liquefying the eflluent product and recovering the hydrogen from the liquefied product by flashing a dry gas portion containing hydro gen therefrom. Yet another object of the present invention is to provide an improved process for the production of hydrogen wherein light paraflins are dehydrogenated, the effluent product is liquefied, the dry gas portion of the liquefied product is flashed to recover the hydrogen, and the hydrogen is further purified by the removal of other gases therefrom. A still further object of the present invention is to provide an improved process for the production of hydrogen wherein light parafiins are dehydrogenated, the effluent product is liquefied, the dry gas portion of the liquefied product is flashed to remove hydrogen therefrom and the remaining liquefied product is distilled to separate saturated from unsaturated products. Another object of the present invention Is to provide a process for the production of hydrogen wherein light paraffins are de'hydrogenated, the effluent product is liquefied, the liquefied product is flashed to remove the dry gas portion including hydrogen therefrom, the remaining liquefied product is separated into saturated and unsaturated fractions and the saturated fraction 18 recycled to the hydrogen production step. These and other objects and advantages of the present invention will be apparent from the following detailed description.

SUMMARY OF THE INVENTION Briefly, in accordance with the present invention, high purity hydrogen is produced in substantial quantities by contacting light paraffinic hydrocarbons with a catalyst comprising an active metal selected from the group consisting of Group VIII and Group VI-B of the Periodic System and a promoting amount of a metal selected from the group consisting of Group I, Group II, Rare Earth, Group IV-A metals of the Periodic System, and mixtures thereof, both deposited on an inert oxide support; liquefying the effluent product; and flashing the liquefied product to remove a dry gas portion therefrom. The invention also provides an integrated process wherein the hydrogen flashed from the liquefied eflluent product is contacted with coal liquids in the presence of a hydrogenation catalyst and under hydrogenation conditions.

Suitable feedstocks for use in accordance with the present invention include any light paraffinic hydrocarbons alone or in combination, such as ethane, propane, n-butane, iso-butane, n-pentane, iso-pentane, etc.

Processing conditions for the hydrogen production reaction are dependent upon the feedstock employed. In general, temperatures between about 900 and 1250" F., pressures between about 100 and 2500 mm. mercury absolute, and liquid hourly space velocities from about 0.1 to 10 may be employed. More specifically, Where ethane is the feedstock, the temperature should be between about 1100 and 1250 F. Where C to C paraflins are the feedstock, a temperature of 900 to 1150 F. should be used. In either case, the remaining conditions may vary over the ranges given.

Hydrogen is recovered from the product stream by liquefying the eflluent product. Such liquefication may be effected by conventional means, such as condensation, compression, etc. The liquefied product is then flashed to remove a dry gas portion therefrom. Such dry gas portion will include hydrogen, methane and ethane, while the remaining liquefied portion will contain propane, ethylene, propylene and other higher boiling hydrocarbons.

The recovered hydrogen may be further purified by cryogenic, adsorption, or diffusion methods or the like.

The separated hydrogen may be compressed and utilized in typical refining and petrochemical operations, such as hydrogenation, hydrotreating, hydrocracking, hydrodealkylation, etc. Preferably, however, the separated hydrogen is contacted with highly unsaturated coal liquids derived from solid coal. Such coal liquids may, for example, be obtained by crushing or grinding solid coal and subjecting the pulverized coal to carbonization or pyrolysis at elevated temperatures to produce liquid products. These liquid products may then be contacted with hydrogen from the previous operation to convert the same to a more saturated, highly aromatic product. It is also known that crushed or ground coal may be contacted with a suitable solvent, at slightly elevated temperatures, such as tetralin, Decalin and other hydrogen transfer s olvents, to thereby produce a solvent extract. By contacting this solvent extract with hydrogen, produced in accordance with the present invention, such extracts can be converted to hydrocarbon materials resembling, in many respects, petroleum crude oils. The only real difference between these hydrogenated coal liquids and petroleum crude oils is that the former contain a higher concentration of aromatics. However, the hydrogenated coal liquids may be processed in conventional refinery schemes which are used for petroleum.

The remaining liquefied eflluent product may then be further separated to separate saturated from unsaturated hydrocarbons. Such separation can be accomplished by distillation, adsorption, solvent extraction, selective polymerization, selective alkylation of aromatics or paraffins, etc. The separated unsaturated products such as ethylene, propylene, n-butylene, iso-butylene, etc., are in and of themselves valuable products of commerce. The saturated or paraflinic products of the separation are then recycled to the initial hydrogen production reaction.

The hydrogenation of the coal liquids may be carried out in the presence of the same catalysts utilized for the hydrogen production reaction. However, any known hydrogenation catalyst may also be employed, such as Group VIII metals, for example, platinum, palladium, rhodium, nickel and cobalt, and Group VI metals, such as molybdenum or tungsten, or various combinations of these metals deposited on a carrier, such as alumina or silica. Hydrogenation conditions may include temperatures from about 450 to 850 F., preferably about 500 to 800 F., pressures of about 4000 to 10,000 p.s.i.g., liquid hourly space velocities from about 0.1 to 10 and hydrogen-to-hydrocarbon mole ratios from about 1 to 20 to 1.

The novel catalysts of the present invention include an active metal from Group VIII of the Periodic System, such as platinum, palladium, rhodium or nickel in concentrations of about 0.5 to 5% by weight based on the finished catalyst, or a Group VI-B metal, such as chromium, molybdenum or tungsten, in amounts of about 5 to 15% by weight of the finished catalyst. The promoter of the present invention may include a Group I metal, such as potassium, rubidium, cesium, etc., a Group II metal, such as calcium, magnesium, strontium, etc., a Rare Earth metal, such as cerium, thorium, etc., a Group IV-A metal, such as tin or lead, or mixtures of these, particularly mixtures of a Group IVA metal with one of the other groups mentioned. The promoters are preferably in their oxide form and are present in amounts of about 1 to 15% by weight based on the weight of the finished catalyst.

Both the active catalytic metal and the promoter are deposited on an inert oxide support, preferably an alumina of the gamma type, such as the bayerite, beta, etc., and boehmite crystalline forms. Other suitable supports of this character may also include other aluminas, silica-alumina, silica, silica-magnesia, alumina-magnesia, silica-zirconia, etc.

The catalysts may be prepared by techniques well known in the art. For example, such preparation may include coprecipitation or impregnation techniques. One may employ extrudates or pellets for impregnation, or powders followed by pelletization or extrusion to yield the finished catalyst. The active metal and the promoter are added by the use of water soluble salts, such as their halides, nitrates, sulfates, acetates, etc. Easily hydrolyzed salts can be kept in solution without decomposition by employing the appropriate inorganic acids. Well-known procedures for drying and calcination of the catalyst may also be employed, such as vacuum drying and calcination in oxidative, neutral and reductive atmospheres, utilizing calcination temperatures of about 800 to 1200" F.

As previously indicated, prior techniques for the proof 16 hours without noticeable reduction in hydrogen production of hydrogen involve dehydrogenation of paraffius duction or deactivation of the catalyst.

TABLE II Run No. 3

Catalyst: 12% (Irma-3%, KzO-2%, S110 on A1203 Feed: Isobutane, 99.6%+

Conditions:

Prerun lineout, F 973 Avg. reaction, F 956 951 952 960 968 976 978 Pressure, p s 1 Q L.H.S.V 1.04 W.H.S.V 0.69 Results: at time Indicated, hr 0.75 3 6. 00 9. 00 12.00 15.00 16.00 Analysis, G 0 mole perc ut:

H1.-- 24. 2 31.1 30.1 29. 0 28. 8 29. 0 29. 4 CH1- 0. 6 0.1 0. 2 0.1 0.1 0.4 0. 6 02s.- 0.3 0. 1 70. 1 70. 1 70. 1 0. 1 70. 1 01--- 0.2 0.3 0.3 0.3 0.3 0.3 0.3 o3= 0.4 0.1 0.1 0 1 0.2 0.2 0.2 i-C4- 56. 7 42.1 43. a 43. 9 44.1 44. a 44. 4 11-01- 0. 1 0.1 0. 1 70. 1 70. 1 70. 1 70. 1 i-Cr- 17. 4 20. 0 25. 8 26.5 26. 4 25. 6 26.1 01-2- 0.1 0.1 0.1 0.1 0 1 0.1 0.0 Carbon on catalyst, wt. percent 2. 60 Conversion of isobutane 24 60 38 81 37.97 38. 26 38.16 37 66 36.84

over catalysts having extremely short cycle times. By way When reference 18 made herein to the Periodic System of contrast, the present process can be carried out over of em 1116 Particular groupings referred to are as Set substantially longer periods of time without serious deforth in the feriodic 0f the Elements, in activation of the catalyst or reduction in the volume of Merck Index, sevfinth edltlon, Merck & 's 1950- hydrogen produced. The following table shows the pro- We claim:

duction of hydrogen from propane utilizing 11 and 88- r q for the production of y e p minute cycles on certain of the catalysts of the present f contacilng paraffinlc hydrocarbons consisting esseninvemiom tially of C to C hydrocarbons w1th a catalyst c0ns1st- 30 ing essentially of a catalytic amount of a Group VI-B metal of the Periodic System, and a promoting amount of a Group lV-A metal of the Periodic System, both deposited on an inert oxide carrier while maintaining conditions of temperature, pressure and space velocity suffi cient to dehydrogenate said parafiinic hydrocarbons;

liquefying the eflluent product and flashing a dry gas portion containing hydrogen therefrom.

TABLE I 2. A process in accordance with claim 1 wherein the promoting metal is in its oxide form. 1$$5 23- 40 3. A process in accordance with claim 1 wherein the inert oxide carrier is a gamma alumina.

4. A process in accordance with claim 1 wherein the 1 2 efiluent product is liquefied by condensation.

Catalyst r 5. A process accordance with claim 1 wherein the IOCHOHKZW A1203 mono risnm A1203 eflluent product 15 hquefied by compression.

Run

Time, minutes 11 88 11 88 References Cited Conversion 39.0 32.9 28.8 26.1 UNITED STATES PATENTS Product dist., mole percent: 2,526,966 10/1950 Oberfell et al. 20864 53- 3 3;; &5; 3,258,420 6/1966 Dalson et al 208-138 Ethane.- 2.7 1.9 1.6 1.4 3,431,195 3/1969 Storch et a1 208-138 ggfgg 2,911,288 11/1959 Viles 23-21212 H s a; g 3 3,018,242 1/1962 Gorin 208--10 9 7 6 55 3,453,202 7/1969 Friedman et al 208-10 1,990,708 2/1935 Pier et a1 208-10 2,863,826 12/1958 Holcomb e161 208-138 3,264,207 8/1966 Pfeiferle 208-138 3,296,118 1/1967 Czajkowski et a]. 208100 3,446,869 5/1969 Nolan 260-6833 3,488,402 1/1970 Michaels et a1. 260-6833 3,531,543 9/1970 Clippinger et. al. 260-6833 HERBERT LEVINE, Primary Examiner The following Table II illustrates the production of hy- U5 CL drogen from iso-butane utilizing a catalyst in accordance with the present invention, and carried out over a period 2524693 260 683-3; 4234513 

